PROJECT SUMMARY/ABSTRACT This K99/R00 award will prepare Dr. Patrick Hannon for an independent research career, with the main goal of providing Dr. Hannon all the necessary technical and professional skills to transition into a career in academia and become a leader in the field of reproductive toxicology. Dr. Hannon has extensive training in elucidating the effects of environmental toxicants on the ovary in rodent models, but in this K99/R00 he will expand his research training and translate these findings into human health and fertility. These goals will be accomplished with the support of Dr. Hannon's enthusiastic and exceptional mentoring team, led by Drs. Thomas Curry and Humphrey Yao. The research proposal and career development plan created by Dr. Hannon with the guidance of his mentoring team will provide Dr. Hannon with new experimental techniques and skills needed to establish an independent research program. In the research training component, Dr. Hannon will elucidate the effects and mechanisms by which phthalates, a class of endocrine-disrupting chemicals, impair ovulation and fertility in humans and rodents. Women of reproductive age are exposed to phthalates on a daily basis because phthalates are incorporated in a myriad of common consumer, medical, building, and personal care products. However, little is known about the effects of environmentally relevant levels of phthalates on ovulation, especially in humans. This is concerning because defects in ovulation are the leading cause of infertility in women. Preliminary data for this proposal are the first to show that an environmentally relevant phthalate mixture inhibits progesterone (P4) production and alters the mRNA levels of P4 receptor (PGR), prostaglandin- endoperoxide synthase 2 (PTGS2), and amphiregulin (AREG) following human chorionic gonadotropin treatment (hCG; analogous to the midcycle luteinizing hormone surge) in human and mouse ovarian cells. P4, PGR, PTGS2, and AREG are known mediators of ovulation. Thus, these findings suggest that phthalate exposure may disrupt ovulation contributing to infertility. A primary human granulosa cell model and mice will be utilized to test the hypothesis that phthalates adversely impact ovulatory processes by altering the levels of ovulatory mediators leading to impaired ovulation and fertility. Specific Aim 1 (Mentored Phase) will determine which ovulatory events are impaired by phthalate exposure. Specific Aim 2 (Mentored and Independent Phases) will elucidate the mechanisms by which phthalates impair these ovulatory processes. Specific Aim 3 (Independent Phase) will establish that phthalate exposure causes impaired ovulation and infertility in vivo. These findings will establish the impact of phthalates on female fertility and reproductive health, while providing Dr. Hannon the necessary research and professional skills for his academic career. Further, the attainment of a greater understanding of the mechanisms of action of phthalates in human samples will begin to provide avenues to intervene on phthalate-induced reproductive dysfunction and infertility.